The present invention relates to electromagnetic transducers, which may for example be employed in information storage systems or measurement and testing systems.
An inductive head used for writing and/or reading magnetic information on a storage media such as a disk or tape includes electrically conductive coil windings encircled by a magnetic core including first and second pole layers. Portions of the pole layers adjacent the media are termed pole tips. The magnetic core is interrupted by a submicron nonmagnetic gap disposed between the pole tips to divert magnetic flux to the media during writing. To write to the media electric current is flowed through the coil, which produces magnetic flux in the core encircling the coil windings, the magnetic flux fringing across the nonmagnetic gap adjacent to the media so as to write bits of magnetic field information in tracks on the media.
The first pole layer may also serve as a magnetic shield layer for a magnetoresistive (MR) sensor that has been formed prior to the pole layers, the combined MR and inductive transducers termed a merged head. A structure in which a magnetic shield layer is disposed adjacent to a first pole layer may be termed a piggyback head. Typically the first pole layer is substantially flat and the second pole layer is curved, as a part of the second pole layer is formed over the coil windings and insulation disposed between the pole layers, while another part nearly adjoins the first pole layer adjacent the gap. The second pole layer may also diverge from a flat plane by curving to meet the first pole layer in a region distal to the media-facing surface, sometimes termed the back gap region, although typically a nonmagnetic gap in the core does not exist at this location.
The curvature of the second pole layer from planar affects the performance of the head. An important parameter of the head is the throat height, which is the distance from the media-facing surface to the point at which the first and second pole layers begin to diverge and are separated by more than the submicron nonmagnetic gap. Because less magnetic flux crosses the gap as the pole layers are further separated, a short throat height is desirable in obtaining a fringing field for writing to the media that is a significant fraction of the total flux crossing the gap.
In addition to the second pole layer being curved from planar, one or both pole layers may also have a tapered width in the pole tip area, to funnel flux through the pole tips. The width of the pole tips, also known as the track width, may be decreased to allow more tracks to be written in a given area. As the track width is decreased, however, it becomes more difficult to efficiently funnel magnetic flux through the pole tips. A magnetic pedestal may be employed between the second pole layer and the second pole tip, in an attempt to obtain sufficient signal strength at the edge of the second pole tip adjacent the gap, which writes to the media.
In one aspect, an inductive transducer is disclosed having a leading pole layer and a leading pole tip, with the pole layer being further removed than the pole tip from a media-facing surface. In another aspect, an inductive transducer is disclosed having a magnetic pedestal disposed between a leading pole layer and a leading pole tip, with at least one of the pedestal and pole layer being further removed than the pole tip from a media-facing surface. In another aspect, a leading pole layer or pedestal may have a surface that slopes away from the media-facing surface with increasing distance forward from the leading pole tip. This summary merely lists a few waspects of the disclosure while the invention is defined by the claims appended below.